Shaft driven bicycle and transmission therefor

ABSTRACT

A two-wheel drive bicycle includes a main frame having a steering head, a seat tube, a cross bar and a hollow downtube. A main drive mechanism includes a housing, a driving spindle, at least one driven ring gear, a first driven shaft and a second driven shaft. The first driven shaft is rotatably connected to the housing and operably coupled to the at least one driven ring gear. The second driven shaft is, likewise, rotatably connected to the housing and operably coupled to the at least one driven ring gear. Front and rear wheel drive mechanisms include a series of shafts that are themselves coupled to and between the first and second driven shafts and the front and rear wheels. The main drive mechanism preferably includes a plurality of driven gears comprising a series of concentrically spaced ring gears. Each ring gear of the plurality of driven ring gears has an inner diametrical surface and an outer diametrical surface. Each outer diametrical surface is configured to slidingly engage the inner diametrical surface of an adjacent ring gear. Further, the main drive mechanism preferably includes a biasing means for biasing each ring gear away from the first driven shaft and the second driven shaft and a selective engagement means for selectively engaging one ring gear of the plurality of ring gears with the first driven shaft and the second driven shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the field of bicycles driven by shafts and,more particularly, to the field of one and two-wheel drive bicycleshaving one or both of the front wheel and the rear wheel driven by aseries of shafts that are themselves coupled to a transmission having aplurality of ring gears.

2. Description of the Prior Art

Two-wheel drive bicycles are known in the art and generally compriseeither a shaft drive, a chain or belt drive, a cable drive or somecombination thereof. For example, U.S. Pat. No. 4,479,660 (Pattison)describes an endless belt drive system for the front wheel that isdriven by the bicycle pedals. In a somewhat similar vein, U.S. Pat. No.4,773,662 (Phillips) describes a second chain drive system for the frontwheel that is driven by an auxiliary hand crank. A cable drive system,on the other hand, is described in U.S. Pat. No. 5,052,705 (Ringle).Instead of being driven by the bicycle pedals or an auxiliary handcrank, the Ringle cable drive is driven by the rotation of the rearwheel, which is itself driven in standard fashion by the bicycle pedals.A similar cable drive is described in U.S. Pat. No. 5,184,838 (Becoat).A combination of chain drives and shafts is described in U.S. Pat. No.5,158,314 (Farras Pinos). In a manner similar to the Ringle cable drive,the Farras Pinos combination drive is driven by the rotation of the rearwheel. A similar combination of chain drives, cable drives and/orflexible shafts is described in U.S. Pat. No. 5,224,725 (Erlston) and inU.S. Pat. No. 5,332,244 (Turner et al.). Other combinations of drivemechanisms are described in, for example, U.S. Pat. No. 6,095,540 (Kim),U.S. Pat. No. 6,161,854 (Christini et al.), U.S. Pat. No. 6,406,047(Sawyer, Jr.) and U.S. Pat. No. 6,419,255 (Chang et al.).

SUMMARY OF THE INVENTION

A two-wheel drive bicycle includes a main frame having a steering head,a seat tube, a cross bar and a hollow downtube. A main drive mechanismincludes a housing, a driving spindle, at least one driven ring gear, afirst driven shaft and a second driven shaft. The housing is connectedto the main frame while the driving spindle is rotatably connected tothe housing as well as to the pedals of the bicycle. The first drivenshaft is rotatably connected to the housing and operably coupled to theat least one driven ring gear. The second driven shaft is, likewise,rotatably connected to the housing and operably coupled to the at leastone driven ring gear.

A front wheel drive mechanism includes a first shaft means rotatablypositioned inside of the hollow downtube and a second shaft meansrotatably positioned inside of a hollow fork tube. The first shaft meanshas a first end operably coupled to the first driven shaft and a secondend operably coupled to the second shaft means. The second shaft meansis operably connected to the front wheel. A rear wheel drive mechanismincludes a third shaft means rotatably positioned inside of a hollowchain stay. The third shaft means has a first end operably coupled tosaid second driven shaft and a second end operably coupled to the rearwheel.

The main drive mechanism preferably includes a plurality of driven gearscomprising a series of concentrically spaced ring gears. Each ring gearof the plurality of driven ring gears has an inner diametrical surfaceand an outer diametrical surface. Each outer diametrical surface isconfigured to engage the inner diametrical surface of an adjacent ringgear. Further, the main drive mechanism preferably includes a biasingmeans for biasing each ring gear away from the first driven shaft andthe second driven shaft and a selective engagement means for selectivelyengaging one ring gear of the plurality of ring gears with the firstdriven shaft and the second driven shaft. A shifter mechanism operatesthe selective engagement means and a user propels the bicycle using astandard pair of bicycle pedals.

Other embodiments of the present invention are contemplated and includeuse of the main drive mechanism to propel either the front wheel or therear wheel in a single wheel drive embodiment or to propel both wheelsin a two wheel drive or dual wheel drive embodiment. Shock absorbingelements for the front and rear wheels, separately or together, are alsocontemplated for use with both the single and dual wheel embodiments.Each of the components that make up the contemplated embodiments,moreover, are constructed using standard materials typically used forconstructing bicycle frames and components, such as, for example,aluminum, steel or titanium. Alternatively, the components may beconstructed using fiber reinforced plastics, which offer superb strengthto weigh ratios when compared to other materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a first embodiment of thepresent invention;

FIG. 2 is a perspective view illustrating the drive train of theembodiment illustrated in FIG. 1;

FIG. 3 is a front view of the front fork appearing in the embodimentillustrated in FIG. 1;

FIG. 4 is a side view of the front fork appearing in the embodimentillustrated in FIG. 1;

FIG. 5 is a perspective view of the triple clamp appearing in theembodiment illustrated in FIG. 1;

FIG. 6 is a front view of the triple clamp appearing in the embodimentillustrated in FIG. 1;

FIG. 7 is a cutaway view of the main drive mechanism taken along theline 7-7 shown in FIG. 1.

FIG. 8 is a perspective view of a driven ring gear;

FIG. 9 is an exploded view of the housing for the main drive mechanismthat appears in the embodiment illustrated in FIG. 1;

FIG. 10 is an exploded view of the biasing mechanism that appears in theembodiment illustrated in FIG. 1;

FIG. 11 is an exploded view of the selective engagement mechanism thatappears in the embodiment illustrated in FIG. 1;

FIG. 12 is a close-up view of a portion of the selective engagementmechanism illustrated in FIG. 11;

FIG. 13 is a cutaway view of the housing used in the rear wheel drivemechanism that appears in the embodiment illustrated in FIG. 1;

FIG. 14 is a cutaway view of a portion of the rear wheel drive mechanismused in the embodiment illustrated in FIG. 1;

FIG. 15 is a front view of a shock absorbing front fork.

FIG. 16 is a perspective view illustrating a full-suspension embodimentof the present invention;

FIG. 17 is a perspective view illustrating the drive train of theembodiment illustrated in FIG. 16; and

FIG. 18 is a cutaway view of a portion of the rear wheel drive mechanismused in the embodiment illustrated in FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a two-wheel drive bicycle 10 includes a mainframe 12, a front fork 14, a front wheel 16, a rear frame 18 and a rearwheel 20. The two-wheel drive bicycle 10 further includes front wheeldrive means 22 for rotatably driving the front wheel 16, rear wheeldrive means 24 for rotatably driving the rear wheel 20 and main drivemeans 26 for rotatably driving both the front wheel drive means 22 andthe rear wheel drive means 24.

More specifically, the main frame 12 includes a steering head 28, a seattube 30, a cross bar 32 and a downtube 34. The cross bar 32 has a firstend 36 and a second end 38. The steering head 28 and the cross bar 32are connected proximate the first end 36 of the cross bar 32, while theseat tube 30 and the cross bar 32 are connected proximate the second end38 of the cross bar 32. The downtube 34 is preferably hollow and has afirst end 40 and a second end 42. The downtube 34 and the steering head28 are connected proximate the first end 40 of the downtube. Theforegoing connections are accomplished using standard techniques knownto those skilled in the art, such as, for example, by welding.Alternatively, press-fit couplings—e.g., press fit couplings 400 and401—may be used to secure the various frame components together. Thebenefit of the latter method is the frame may be disassembled to provideeasier access to the components that comprise the drive means asdescribed below. A seat 44 is height-adjustably connected to the seattube 30, also using standard techniques known to those skilled in theart, such as, for example, by a seat post 46 that is slidably engagedwith the seat tube 30.

Referring to FIGS. 3-5, the front fork 14 is pivotally connected to thesteering head 28 and functions, among other things, to steerably androtatably connect the front wheel 16 to the main frame 12. The frontfork 14 generally includes a triple clamp 50, a first fork tube 52 and asecond fork tube 54. The first fork tube 52 has a first end 56 and asecond end 58 and includes a hollow portion 60 that extends from thefirst end 56 to the second end 58. The hollow portion 60 is used tohouse components that comprise part of the front wheel drive means 22,as is discussed below.

The triple clamp 50 secures the first fork tube 52 and the second forktube 54 to the main frame 12 and also houses a first set of spur gears48 that comprise part of the front wheel drive means 22. The tripleclamp 50 is preferably made of aluminum, but may be made of any othercomparably high-strength and light-weight material. The triple clamp 50has a hollow portion 62 that is sized and configured to house the firstset of spur gears 48 therein. The triple clamp 50 also has a set ofrecess portions 64 that provide means with which to secure a set ofshafts 66 upon which various ones of the first set of spur gears 48 arerotatably mounted. The triple clamp 50 is preferably constructed as atwo-piece assembly, whereby an upper piece 67 and a lower piece 68 fittogether at a parting line 69 and are secured together by bolts 70. Thetwo-piece assembly allows the first set of spur gears 48 and relatedparts—e.g., bearings and bushings—that comprise part of the front wheeldrive means 22 to be assembled inside of the triple clamp 50.

The first fork tube 52 and the second fork tube 54 are preferably hollowand constructed using standard light weight and high strength materialsgenerally used to construct bicycle front forks, such as, for example,aluminum or titanium. The first fork tube 52 has an upper end 53 thatextends through a first aperture 51 that is formed in the triple clamp50. Similarly, the second fork tube 54 has an upper end 57 that extendsthrough a second aperture 55 that is formed in the triple clamp 50. Theupper ends 53, 57 of the first and second fork tubes 52, 54 are,preferably, press fit against both the upper piece 67 and the lowerpiece 68 of the triple clamp 50. The press fit for both tubes isaccomplished using, for example, a pair of bolts 250 and a slit 251 thatis machined from the upper and lower pieces 67, 68 of the triple clamp50. Following positioning of the fork tubes in the apertures 51, 55, thebolts 250 are tightened, thereby locking the upper ends 53, 57 in place.

Referring again to FIG. 1 and also to FIGS. 13 and 14, the rear frame 18is connected to the main frame 12 and functions, among other things, torotatably connect the rear wheel 20 to the main frame 12. The rear frame18 generally includes a first chain stay 72, a second chain stay 73, afirst seat stay 74 and a second seat stay 75. Each of the chain stays72, 73 have first ends 76 and second ends 77, while each of the seatstays 74, 75 also have first ends 78 and second ends 79. The first chainstay 72 has a hollow portion 80 that extends from the first end 76 tothe second end 77. The hollow portion 80 is used to house components ofthe rear wheel drive means 24, as is discussed below.

The seat stays 74, 75 are preferably constructed of aluminum, but may beconstructed of other high-strength and low-weight materials that aretypically used in constructing bicycle frames. The first ends 78 of theseat stays 74, 75 are secured to the seat tube 30 using, preferably, abracket means 82. A bracket means 82 permits the rear frame 18 to beremoved from the main frame 12 for repair or maintenance of the rearwheel drive means 22. The second ends 79 of the seat stays 74, 75 areconnected to the second ends 77 of the chain stays 72, 73 through use ofplate members 83, 84. The second ends 79 of the seat stays 74, 75 arepreferably bolted to the plate members 83, 84 as are the second ends 77of the chain stays 72, 73. Alternatively, the plate members 83, 84 maybe welded to one of the second ends 79 of the seat stays 74, 75 and thesecond ends 77 of the chain stays 72, 73, while the other of the pair ofsecond ends 77, 79 is bolted to the plate members 83, 84.

The chain stays 72, 73 are also preferably constructed of aluminum, butmay be constructed of other high-strength and low-weight materials thatare typically used in constructing bicycle frames. The first ends 76 ofthe chain stays 72, 73 are secured to the housing 85 using, preferably,a pair of bracket means 71, 81. The bracket means, 71, 81, together withthe bracket means 82 above described with reference to the seat stays74, 75 permit the rear frame 18 to be removed from the main frame 12 forrepair or maintenance of the rear wheel drive means 22. The second ends77 of the chain stays 72, 73 are secured to the plate members 83, 84 ina manner similar to that used to secure the seat stays 74, 75, that is,through bolts or by welding.

Referring now to FIGS. 1 and 2 and also to FIGS. 7-12, a main drivemeans 26 is connected to the main frame 12 and functions, among otherthings, to operate the front wheel drive means 22 and the rear wheeldrive means 24, both of which are discussed below. The main drive means26, preferably, includes a housing 85, a driving spindle 86, a pluralityof driven ring gears 87, a first driven shaft 88 and a second drivenshaft 89. In addition, a biasing means 92 biases the plurality of drivenring gears 87 away from the first driven shaft 88 and the second drivenshaft 89, while a selective engagement means 94 selectively engages aselect one of the plurality of driven ring gears 87 with the firstdriven shaft 88 and the second driven shaft 89. The main drive means 26is operated by a user through a pair of foot pedals 90, which arethemselves mounted to the driving spindle 86 through a pair of cranklevers 91.

More specifically, and by way of example, the main drive means 26includes a series of ten driven ring gears 95A-95J. With reference toFIGS. 7 and 8, each driven ring gear—95C, for example—has an innercircumferential surface 96 and an outer circumferential surface 97 and afront surface 98 and a back surface 99. Spaced along the innercircumferental surface 96 and the outer circumferential surface 97 are aseries of engaging teeth 100 and a series of engaging recesses 101,respectively. Each tooth of the series of engaging teeth 100 is sizedand positioned to slidingly engage a corresponding recess on the outercircumferential surface of the immediately adjacent and smaller diameterdriven ring gear (i.e., ring gear 95B). Similarly, each recess of the ofthe series of engaging recesses 101 is sized and positioned to slidinglyengage a corresponding tooth on the inner circumferential surface of theimmediately adjacent and larger diameter driven ring gear (i.e., ringgear 95D). Furthermore, the constant radius portions 102, 103 of theinner circumferential surface 96 and the outer circumferential surface97 are sized in radius 104 to slidingly engage the correspondingconstant radius portions of the adjacent ring gears.

When each one of the plurality of driven ring gears 87—e.g., the seriesof ten driven ring gears 95A-95J—is sized and configured in the fashionabove described, a cluster of ring gears results whereby any one of thecluster may be setoff a small distance 105 from a bias plane 106 thatthe front surface 98 of each of the remaining gears otherwise resides.As explained below, this feature permits the selective engagement means94 to displace a select ring gear—e.g., ring gear 95C—a small distance105 from its otherwise biased position so that the select ring gearengages both the first driven shaft 88 and the second driven shaft 89.An inter-gear tolerance—i.e., the spacing between the innercircumferential surface and the outer circumferential surface ofadjacent gears—of about one one-hundredth ({fraction ({fraction(1/100)})}) of an inch to about twenty one-hundredths ({fraction({fraction (20/100)})}) of an inch is believed to enable a single set ofbiasing means 92 and selective engagement means 94 to displace a selectring gear the small distance 105 without binding against adjacent gears.Otherwise, a second set of biasing means and selective engagement meansmay be positioned on the opposite side of the housing (that is, spaced180 degrees from the biasing means 92 and the selective engagement means94) in a manner similar to that described above.

The series of ten driven ring gears 95A-95J are assembled consistentwith the foregoing discussion. More specifically, the driven ring gearhaving the smallest radius 104—i.e., ring gear 95A—is slidingly engagedwith the driving spindle 86. The driving spindle 86 has a series ofengaging recesses 107 that are sized and positioned to correspond withthe series of engaging teeth 100 that reside on the innercircumferential surface 96 of the ring gear having the smallest radius104—i.e., ring gear 95A. The ring gear having the next largest radius104—i.e., ring gear 95B—is then positioned about the former ring gear,with the process being repeated until the ring gear having the largestradius 104—i.e., ring gear 95J—is placed on the cluster.

A first driving spindle bearing 108 and a second driving spindle bearing109 rotatably secure the driving spindle 86 is the housing 85. The firstand second spindle bearings 108, 109 are preferably press fit onto thedriving spindle 86 as well as into first and second bearing recesses113, 114 of the housing 85. The housing 85 is itself preferably formedby joining a first housing section 110 and a second housing section 111together. Dividing the housing 85 into first and second housing sections110, 111 facilitates assembly and disassembly of the main drive means26. The first and second housing sections 110, 111 may be held togetherusing any suitable means, such as clamp members 112.

Referring to FIGS. 7-10, a biasing means 92—e.g., biasing mechanism115—includes structure whose function is to bias the plurality of drivenring gears 87 a short distance (on the order of one-sixteenth of aninch) away from the first driven shaft 88 and the second driven shaft89. A preferred embodiment of the biasing means 92 includes a housingmember 116 having a plurality of guide tubes (or recesses) 117A-117Jformed therein. Slidably engaged with each individual guide tube—e.g.,guide tube 117J—is a spring means 118 and a roller means 119. The springmeans 118 biases the roller means 119 against a corresponding drivenring gear—e.g., ring gear 95J—and hence biases the driven ring gear 95Jaway from the first and second driven shafts 88, 89. The roller means119 includes, for example, a base member 120, a roller 121 and a rollershaft 122. The spring means 118—e.g., coil spring 123—has for reactionsurfaces the back side 124 of the housing member 116 and the base member120. The housing member 116 is secured to the housing 85 using clampmembers 125, which are themselves secured to the housing 85 using anysuitable means, such as by bolts (not shown). A recess 126 is formed inthe housing 85 and provides means by which the housing member 116 may beheld securely to the housing 85 and protrude through the wall of thesecond housing section 111.

With the biasing means 92—e.g., biasing mechanism 115—assembled in thisfashion, the roller 121 is continually held in contact with itscorresponding driven ring gear—e.g., ring gear 95J. Preferably, theroller 121 is sized to roll over the individual teeth 127 that reside onthe front surface 98 of the ring gear, meaning that the outer diameter128 of the roller 121 should be at least as large as the distance 129between the centers of adjacent teeth 127. Alternatively, a groove (notillustrated) may be machined through the center of each of theindividual teeth 127 such that the roller 121 makes smooth contactagainst a flat surface on the front surface 98 of the ring gear, ratherthan against the individual teeth 127.

Referring to FIGS. 7-12, a selective engagement means 94—e.g., selectiveengagement mechanism 130—includes structure whose function is toselectively engage a select one of the plurality of driven ring gears 87with the first driven shaft 88 and the second driven shaft 89. Apreferred embodiment of the selective engagement means 94 includes ahousing member 131 having a plurality of guide tubes (or recesses)132A-132J formed therein. A second housing member 140 has a track 141formed therein that is sized and configured to permit slidableengagement of a cam member 142 therewith.

Slidably engaged with each individual guide tube—e.g., guide tube132J—is a roller means 133. The roller means 133 includes, for example,a base member 134, a roller 135 and a roller shaft 136. The base member134 includes a rounded portion 137 that is sized and configured to makesliding contact with a similarly rounded portion 138 of the cam member142. At the periphery 143 of each guide tube 132 is a protuberance 144that functions to maintain each base member 134 inside its individualguide tube 132. The distance 145 that each base member 132 extendsbeyond the periphery 143 is essentially equal to the setoff distance105, after making allowances for tolerances among the various componentsof the biasing means 92 and the selective engagement means 94. Thehousing member 131 is positioned adjacent the second housing member 140and the combination is secured to the housing 85 using clamp members125, which are themselves secured to the housing 85 using any suitablemeans, such as by bolts (not shown). A recess 148 is formed in thehousing 85 and provides means by which the housing member 131, 140 maybe held securely to the housing 85 and protrude through the wall of thefirst housing section 110.

With the selective engagement means 94—e.g., selective engagementmechanism 130—assembled in this fashion, each roller 135 is heldadjacent its corresponding driven ring gear—e.g., ring gear 95E.Preferably, each roller 135 is sized and configured to roll over theback surface 99 of its corresponding ring gear. The cam member 142 ismoved along the track 141 by, for example, a cable 147, which is itselfconnected to a shifting mechanism (not illustrated), such as a ratchetshifter. The shifting mechanism operates to incrementally slide the cammember 142 along the track 141 through movement of the cable 147. Ateach increment, the shift mechanism positions the cam member 142immediately adjacent a base member 134 that itself corresponds with aselect driven ring gear—e.g., driven ring gear 95C. The cam member 142will force the base member 134 a distance 145 into the guide tube 132,which distance is sufficient to engage the select driven ring gear withthe first and second driven shafts 88, 89. In other words, the cammember 142 forces the teeth on the select ring gear—e.g., ring gear95C—into engagement with the corresponding teeth (or splines) on thefirst and second driven shafts 88, 89. In this manner, the select ringgear is said to be selectively engaged with the first and second drivenshafts. The cam member 142 is biased by a spring means—such as, forexample, coil spring 146—so that the cam member 142 will be biasedtoward one end of the track 141 upon release of the ratchet shiftingmechanism. In other words, the coil spring 146 serves a similar functionto that provided by the coil springs that serve to bias the front andrear chain derailleur mechanisms that are found on typical multi-speedbicycles.

Referring again to FIGS. 2, 7 and 9, the first and second driven shafts88, 89 are rotatably mounted in the housing 85 and function to transfertorque supplied by the rider to the driving spindle 86 to the frontwheel and rear wheel driving means 22, 24. For example, the first drivenshaft 88 has a first end 150 that is rotatably secured in the housing 85by a bearing 151 that is itself press fit onto the first driven shaft 88proximate its first end 150. The bearing 151 is secured to the housing85 by a recess portion 152 that is formed in the housing 85. The firstdriven shaft 88 has a second end 153 that extends away from the firstend 150 and toward the driving spindle 86. The second end 153 has areduced diameter portion 155 that is sized and configured to fit into arecess 156 that resides in a sleeve 154 that fits over the drivingspindle 86. A second bearing 157 is fit into the recess 156 andfunctions to rotatably secure the second end 153 of the first drivenshaft 88. The second driven shaft 89 is rotatably secured to and withinthe housing 85 is a similar fashion as that used to rotatably secure thefirst driven shaft 88 to and within the housing 85. It is noted thatwhen the first and second driven shafts 88, 89 are so secured, the biasplane 106 in which the front surface 98 of each of the plurality ofdriven ring gears 87 resides is located approximately the setoffdistance 105 away from driving splines 158 that are cut into the firstand second driven shafts 88, 89. The driving splines 158 extend thelength of the first and second driven shafts 88, 89 and are sized andconfigured to engage each one of the plurality of driven ring gears 87.

With the main driving means constructed and assembled as abovedescribed, the first and second driven shafts 88, 89 rotate uponrotation of the driving spindle 86 by a user. The biasing means 92,operating in conjunction with the selective engagement means 94, ensurethat a select one of the plurality of driven ring gears 87 will be inmechanical engagement with the first and second driven shafts 88, 89 atany particular time. Different gearing rations are obtainable byselecting a different one of the plurality of driven ring gears 87 toengage the first and second driven shafts 88, 89. For example, arelatively low-torque, but high-speed gear ratio is obtained byselecting the largest diameter ring gear—i.e., ring gear 95J—as opposedto the smallest diameter ring gear—i.e., ring gear 95A, which willproduce the highest torque, but lowest speed gear ratio. This is similarto the operation of typical multi-speed bicycles wherein the largestdiameter gear of the front set of gears (i.e., the set of gears drivenby the pedals) is used to produce the highest speeds (but lowest torque)and the smallest diameter gear of the front set of gears is used toproduce the lowest speed (but highest torque).

Referring to FIGS. 3-6, the front wheel drive means 22 functions torotatably drive the front wheel 16. A preferred embodiment of the frontwheel drive means 22—e.g., front wheel drive mechanism 160—includes afirst shaft means 161 and a second shaft means 162, together with anintermediate shaft 220 and a first set of spur gears 48. The first shaftmeans 161 has a first end 163 and a second end 164. The first end 163 isoperably coupled to the first end 150 of the first driven shaft 88. Theterm “operably coupled” herein above and below refers interchangeably to“shaft-to-shaft” or to “shaft-to-wheel” couplings—using shafts, gears,universal joints and the like—whereby rotation of a driving shaftproduces rotation of a driven shaft or wheel.

A preferred means of operably coupling the first end 163 of the firstshaft means 161 to the first end 150 of the first driven shaft 88 isaccomplished with a universal joint 165. The universal joint 165 hasfemale spline structure at both ends (not illustrated) that engagecorresponding male spline structure that is formed at the ends of thefirst driven shaft 88 and the first shaft means 161. Use of a universaljoint 165 permits transmission of rotary torque from the first drivenshaft 88 to the first shaft means 161. The first shaft means 161 ispreferably housed in the downtube 34. A pair of bearings 166 arepositioned between the outer diameter of the first shaft means 161 andthe inner diameter of the downtube 34 and enable the first shaft means161 to rotate within the downtube 34.

The second shaft means 162 has a first end 167 and a second end 168. Thefirst end 167 is operably coupled to the second end 164 of the firstshaft means 161, as is discussed below. The second end 168 is operablycoupled to the front wheel 16 through use of, preferably, a drivingbevel gear 169 mounted on the second end 168 of the second shaft means162. The driving bevel gear 169 engages a driven bevel gear 171 that isitself connected to a hub 170. The driven bevel gear 171 has a raisedportion 172 upon which the gear teeth (not referenced) are located. Thesecond shaft means 162 extends through the hollow portion of the firstfork tube 52 and is rotatably mounted therein using a pair of bearings173. An aperture 174 is formed through the first fork tube 52 at alocation proximate the location of the driving bevel gear 169 andenables engagement of the driving bevel gear 169 with the driven bevelgear 171. The raised portion 172 of the driven bevel gear 171 extends,for example, through the aperture 174 to engage the driving bevel gear169 mounted on the second shaft means 162. The rim, tire and spokes ofthe front wheel 16 are all otherwise connected to the hub 170 in typicalfashion.

Referring to FIGS. 3-5, the first end 167 of the second shaft means 162is operably coupled to the second end 164 of the first shaft means 161through use, preferably, of an intermediate shaft means 220 that extendsthrough a portion of the steering head 28 together with the previouslyreferenced first set of spur gears 48. More specifically, theintermediate shaft means 220 has a first end 221 and a second end 222.The first end 221 is operably coupled to the second end 164 of the firstshaft means 161 through use, preferably, of a driven bevel gear 223mounted on the first end 221 of the intermediate shaft means 220. Thedriven bevel gear 223 engages a driving bevel gear 224 mounted on thesecond end 164 of the first shaft means 161. The driven bevel gear 223and the driving bevel gear 224 are mounted on and engage the ends oftheir respective shaft means 220, 161 using typical mounting andengaging means, such as, for example, spline fits (not referenced).

The second end 222 of the intermediate shaft means 220 is operablycoupled to the first end 167 of the second shaft means 162 through useof the first set of spur gears 48. Preferably, the first set of spurgears 48 includes four individual gears 260-263. The center pair of spurgears 261, 262 rotate on corresponding shafts 66 whose ends arepositioned in the recess portions 64 of the triple clamp 50. Bearingmeans, such as, for example, roller bearings (not illustrated orreferenced), are positioned between each one of the center pair of spurgears 261, 262 and their corresponding shaft 66. The driving spur gear263 is secured to the second end 222 of the intermediate shaft means 220using, for example, a spline fit (not referenced). Rotation of thedriving spur gear 263 causes the center pair of spur gears 261, 262 torotate and, in turn, causes the driven spur gear 260 to rotate. Thedriven spur gear 260 is secured to the first end 167 of the second shaftmeans 162 using, for example, a spline fit (not referenced). The firstend 167 of the second shaft means 162 extends into an aperture or recessthat itself extends into the fork tube cap 265. Similarly, the secondend 168 of the second shaft means 162 extends into an aperture or recess267 that extends into the bottom of the first fork tube 52 or,alternatively or in conjunction therewith, a bearing 268 is positionedat a location below the driving bevel gear 169.

The intermediate shaft means 220 is rotatably mounted in a fork stem 226using a pair of bearings 225. The fork stem 226 is itself secured to thetriple clamp 50 using standard techniques known to those skilled in theart, such as, for example, by press fit or by welding (not illustrated)The fork stem 226 is also pivotally mounted to the steering head 28using a second set of bearings 227. An aperture 228 is provided in thefork stem 226 to permit the driving bevel gear 224 to engage the drivenbevel gear 223. The handle bars of the bicycle are connected to theupper end of the fork stem 226 using standard techniques.

With the front wheel drive means 22—i.e., front wheel drive mechanism160 constructed as above described, driven rotation of the front wheel16 results from driving rotation of the first driven shaft 88 which, asdescribed above with respect to the main drive means 26, is driven byrotation of the driving spindle 86 (and which is driven by the pedals90). Of course, driving rotation of the front wheel 16 would producedriven rotation of the first driven shaft 88, which is undesirable asthe bicycle would not be able to “coast” without the pedals 90 turningin response. Thus, a one-way clutch means is positioned at some pointalong the set of component parts that make up the front wheel drivemeans 22. Preferably, a one-way clutch means—e.g., a ratchet and ballbearing or roller type freewheel mechanism 270—is positioned between thedriven bevel gear 171 and the hub 170. Alternatively, the one-way clutchmeans may be positioned between the first driven shaft 88 and itscorresponding universal joint 150. The preferable approach, however, isto position the one-way clutch between the driven bevel gear 171 and thehub 170, as such will eliminate rotation of the various components ofthe front wheel drive means 22 during coasting. Such use of ratchet andball bearing or roller type freewheel mechanisms is known in the art andis described variously in U.S. Pat. No. 479,470 (Smallwood), U.S. Pat.No. 4,943,077 (Lin et al.), U.S. Pat. No. 5,184,838 (Becoat), U.S. Pat.No. 5,299,819 (Leu) and U.S. Pat. No. 6,095,540 (Kim), the disclosure ofwhich patents is incorporated by reference.

The rear wheel drive means 24 functions to rotatably drive the rearwheel 20. Referring to FIGS. 2, 13 and 14, a preferred embodiment of therear wheel drive means 24—e.g., rear wheel drive mechanism 180—includesa third shaft means 181, together with a second set of spur gears 186.The third shaft means 181 has a first end 183 and a second end 184. Thefirst end 183 is operably coupled to the first end 185 of the seconddriven shaft 89 while the second end 184 is operably coupled to the rearwheel 20. The third shaft means 181 is rotatably housed within thehollow portion 80 of the first chain stay 72.

Referring to FIG. 13, a preferred approach to operably coupling thefirst end 183 of the third shaft means 181 to the first end 185 of thesecond driven shaft 89 is through use of a second set of spur gears 186that are mounted within a housing 187. The housing 187 is constructedsimilarly to the triple clamp 50. More specifically, a hollow portion188 is sized and configured to permit the second set of spur gears 186to be housed therein. The housing 187 has recess portions 189 thatsecure the individual shafts 190 upon which certain ones of the secondset of gears 186 rotate. The housing 187 is preferably constructed as atwo-piece assembly, whereby a first piece 191 and a second piece 192join together at a parting line 193 and are held together by bolts 194.The two-piece assembly allows the second set of gears 186 and relatedparts—e.g., bearings and bushing—to be assembled and disassembled. Thehousing 187, following assembly, is then secured to the housing 85 ofthe main drive means 26 through use of a bracket 195 and bolts 196.

Preferably, the second set of spur gears 186 includes four individualgears 270-273. The center pair of spur gears 271, 272 rotate oncorresponding shafts 190 whose ends are positioned in the recessportions 189 of the housing 187. Bearing means, such as, for example,roller bearings (not illustrated or referenced), are positioned betweeneach one of the center pair of spur gears 271, 272 and theircorresponding shaft 190. The driving spur gear 273 is secured to thefirst end 185 of the second driven shaft 89 using, for example, a splinefit (not referenced). Rotation of the driving spur gear 273 causes thecenter pair of spur gears 271, 272 to rotate and, in turn, causes thedriven spur gear 270 to rotate. The driven spur gear 270 is secured tothe first end 183 of the third shaft means 181 using, for example, aspline fit (not referenced).

The second end 184 of the third shaft means 181 is operably coupled tothe rear wheel 20 through, preferably, a driving bevel gear 200 mountedon the second end 184 of the third shaft means 181. The driving bevelgear 200 engages a driven bevel gear 202 that is itself connected to ahub 201. The driven bevel gear 202 has a raised portion 203 upon whichthe gear teeth (not referenced) are located. The third shaft means 181extends through the hollow portion 80 of the first chain stay 72 and isrotatably mounted therein using a pair of bearings 204. An aperture 205is formed in the first chain stay 72 proximate the location of thedriven bevel gear 200 and enables engagement of the driving bevel gear200 and the driven bevel gear 202. The raised portion 203 of the drivenbevel gear 202 extends, for example, through the aperture 205 to engagethe driving bevel gear 200 mounted on the second shaft means 181. Therim, tire and spokes of the rear wheel 20 are all otherwise connected tothe hub 201 in typical fashion.

As with the front wheel drive means 22 above described, driven rotationof the rear wheel 20 results from driving rotation of the second drivenshaft 89 which, as described above with respect to the main drive means26, is driven by rotation of the driving spindle 86 (and which is drivenby the pedals 90). Of course, driving rotation of the rear wheel 20would produce driven rotation of the second driven shaft 89 in a similarmanner to that described above with respect to the front wheel 16 andthe first driven shaft 88, which is likewise undesirable as the bicyclewould not be able to “coast” without the pedals 90 turning also. Thus, aone-way clutch means is also positioned at some point along the set ofcomponent parts that make up the rear wheel drive means 24. Preferably,a one-way clutch means—e.g., a ratchet and ball bearing type freewheelmechanism 280—is positioned between the driven bevel gear 202 and thehub 201. Alternatively, the one-way clutch means may be positionedbetween the second driven shaft 89 and its corresponding driving spurgear 273. The preferable approach, however, is to position the one-wayclutch between the driven bevel gear 202 and the hub 201 in a fashionsimilar to that described previously with respect to the front wheel 16,as such will eliminate rotation of the various components of the rearwheel drive means 24 during coasting.

The foregoing description focuses on a two-wheel drive bicycle having arigid front fork. A two-wheel drive bicycle having a shock-absorbingfront fork is also contemplated. Referring to FIGS. 15-17, for example,a shock-absorbing front fork 300 is illustrated having a firsttelescoping tube assembly 302 and a second telescoping tube assembly304. The first telescoping tube assembly 302 includes an upper fork tube306 and a lower fork tube 308, while the second telescoping tubeassembly 304, likewise, includes an upper fork tube 310 and a lower forktube 312. The upper fork tubes 306, 310 are slidably engaged with theirrespective lower fork tubes 308, 312 in a manner generally known to onehaving skill in the art of shock absorbers for bicycles. For example,U.S. Pat. No. 5,269,549 (Wilson et al.), U.S. Pat. No. 5,597,169(Bradbury) and U.S. Pat. No. 5,848,675 (Gonzalez) describe theconstruction and operation of various types of bicycle shock absorbersand the specific components used therein. The disclosure of each ofthese patents is incorporated herein by reference.

In contrast to certain of the components of the front fork 14 previouslydescribed, the shock-absorbing front fork 300 includes a telescopingsecond shaft means 314. The telescoping second shaft means 314 includesan upper shaft 316 and a lower shaft 318. The upper shaft 316 is,preferably, slidably engaged with and inside of the lower shaft 318.Slidable engagement of the upper and lower shafts 316, 318 isaccomplished using a spline fit (not referenced). To permit relativesliding movement between the upper and lower fork tubes 306, 308, thelower shaft 318 includes an over-length section 320 of the spline fitwhereby the upper shaft 316 is able to slide into the over-lengthsection 320 consistent with the upper fork tube 306 sliding into thelower fork tube 308. Of course, the over-length section 320 mustnecessarily accommodate the full travel of the shock absorber—that is,the over-length section 320 must have a longitudinal dimension 322 atleast as great as the distance the upper tube 306 is permitted to slideinside of the lower tube 308. Otherwise, the travel of theshock-absorbing front fork 300 may be limited by the longitudinaldimension 322 of the over-length section 320.

Further contrasting certain of the components of the front fork 14previously described, the shock-absorbing front fork 300 also includestwo pair of bearings 324, 326. An upper pair of bearings 324 serve torotatably mount the upper shaft 316 inside of the upper fork tube 306.Similarly, a lower pair of bearings 326 serve to rotatably mount thelower shaft 318 inside of the lower fork tube 308.

Shock absorbing components, such as those described in the foregoingreferenced U.S. patents, are positioned in the second telescoping tubeassembly 304. For example, a set of elastopolymer bumpers 330 may bepositioned in the second telescoping tube assembly as disclosed by U.S.Pat. No. 5,269,549 (Wilson et al.) and U.S. Pat. No. 5,597,169(Bradbury). This latter patent, moreover, discloses an adjustable travelassembly that may be positioned in the second telescoping tube assembly.More specifically, a compression rod 331 extends from the bottom of thelower fork tube into the upper fork tube. A pair of reboundelastopolymer bumpers 332 are positioned between the flange 333 of thecompression rod 331 and the lower end 334 of the upper fork tube 310.The travel of the shock absorber is shortened or lengthened byrepositioning bumpers from the rebound set 332 to the main set 330 andvice versa. The benefit of the adjustable travel assembly is that anadjustable travel shock absorber results, which can be accommodated bysizing the longitudinal dimension 322 of the over-length section 320 toallow for an extended travel configuration similar to that disclosed byU.S. Pat. No. 5,597,169 (Bradbury).

Referring now to FIGS. 16-18, a shock-absorbing rear frame 350, whichleads to a full suspension bicycle when combined with theshock-absorbing front fork 300, is illustrated. The shock-absorbing rearframe 350 differs from the previously described rigid rear frame 18 inthat a hinge means 352 is added to the chain stays and a universal joint354 is added to the third shaft means. A standard rear shock 362absorber is also added at the point of connection of the seat stays andthe seat post. The hinge means 352 can be provided by a simple pin orbolt 356 that extends through apertures that are formed in hinges 364positioned at a point intermediate the ends of the chain stays. Theuniversal joint 354 is positioned proximate the hinge means 352 and isaccommodated by cutting the third shaft means in two pieces 358, 360 andpositioning the universal joint 354 over the cut ends of the third shaftmeans (a small amount of the third shaft means may be removed to makeroom for the universal joint 354).

The above description is directed primarily toward a two-wheel drivebicycle with either a rigid front fork and rear frame or a shockabsorbing front fork and rear frame. Nonetheless, it should beappreciated that the main drive means 26 described above may also beused for single-wheel drive bicycles. For example, the front wheel drivemeans 22 described above can be eliminated, resulting in a bicyclecharacterized by the main drive means 26 and the rear wheel drive means24. Similarly, the rear wheel drive means 24 may be eliminated,resulting in a bicycle characterized by the main drive means 26 and thefront wheel drive means 22. In either of the latter cases, only one ofthe driven shafts of the main drive means 26 will be necessary foroperation of the bicycle.

Furthermore, it is contemplated that the components of the abovedescribed embodiments can be constructed from materials that exhibithigh strength and low weight characteristics. For example, and as notedabove, all the components of the above described embodiments may beconstructed of either aluminum or titanium or of similar materialscommonly used in the construction of bicycle frames and components.Preferably, moreover, each of the shaft means and various gears thatmake up the front and rear wheel drive means and the main drive meansmay be constructed of fiber reinforced plastics, which offer superbstrength to weight ratios when compared to aluminum, for example.Pulltrusion manufacturing techniques, moreover, may also be used inmanufacturing the shaft components. Such manufacturing techniques areperformed, for example, by Strongwell Corporation of Bristol, Va.

The two-wheel drive bicycle 10 and the alternative single-wheel bicycleand shock absorbing alternatives have been described with reference toparticular embodiments in the foregoing description. Nonetheless,various other modes for carrying out the invention are contemplated asbeing within the scope of the claims that follow and that particularlypoint out and distinctly claim the subject matter which is regarded asthe invention.

1. A two-wheel drive bicycle, comprising: a main frame, said main frameincluding a steering head, a seat tube, a cross bar and a hollowdowntube, said cross bar having a first end and a second end, said firstend of said cross bar being connected to said steering tube and saidsecond end of said cross bar being connected to said seat tube, saidhollow downtube having a first end and a second end, said first end ofsaid hollow downtube being connected to said steering head; a main drivemechanism, said main drive mechanism including a housing, a drivingspindle, at least one driven ring gear, a first driven shaft and asecond driven shaft, said housing being connected to said main frame,said driving spindle being rotatably connected to said housing andslidingly engaged with said at least one driven ring gear, said firstdriven shaft being rotatably connected to said housing and selectivelyengaged with said at least one driven ring gear, and said second drivenshaft being rotatably connected to said housing and selectively engagedwith said at least one driven ring gear; a front fork, said front forkincluding a hollow fork tube having a first end and a second end, saidfirst end of said hollow fork tube being pivotally connected to saidsteering head; a front wheel, said front wheel being rotatably connectedto said front fork proximate said second end of said hollow fork tube; arear frame, said rear frame including a seat stay and a hollow chainstay, said seat stay having a first end and a second end, said first endof said seat stay being connected to said seat tube, said hollow chainstay having a first end and a second end, said first end of said hollowchain stay being connected to said housing and said second end of saidhollow chain stay being connected to said second end of said seat stay;a rear wheel, said rear wheel being rotatably connected to said rearframe proximate said second end of said chain stay; a front wheel drivemechanism, said front wheel drive mechanism including a first shaftmeans rotatably positioned inside of said hollow downtube and a secondshaft means rotatably positioned inside said hollow fork tube, saidfirst shaft means having a first end operably coupled to said firstdriven shaft and a second end, said second shaft means having a firstend operably coupled to said second end of said first shaft means and asecond end operably coupled to said front wheel; and a rear wheel drivemechanism, said rear wheel drive mechanism including a third shaft meansrotatably positioned inside of said hollow chain stay, said third shaftmeans having a first end operably coupled to said second driven shaftand a second end operably coupled to said rear wheel.
 2. The two-wheeldrive bicycle of claim 1, wherein said main drive mechanism includes aplurality of driven ring gears, said plurality of driven ring gearscomprising a series of concentrically spaced ring gears, each ring gearof said plurality of driven ring gears having an inner diametricalsurface and an outer diametrical surface, each said outer diametricalsurface being configured to engage the inner diametrical surface of anadjacent ring gear.
 3. The two-wheel drive bicycle of claim 2, whereinsaid main drive mechanism further includes: biasing means for biasingeach ring gear of said plurality of driven ring gears away from saidfirst driven shaft and said second driven shaft and selective engagementmeans for selectively engaging one of said plurality of ring gears withsaid first driven shaft and said second driven shaft.
 4. The two-wheelbicycle of claim 3, wherein said biasing means includes: a firstplurality of roller means for rolling contact with said plurality ofdriven ring gears, each one of said first plurality of roller meansbeing positioned adjacent to and in contact with a corresponding one ofsaid plurality of driven ring gears, a plurality of spring means, eachone of said plurality of spring means being positioned adjacent to andin contact with a corresponding one of said first plurality of rollermeans, guide means for maintaining each one of said first plurality ofroller means in alignment with said corresponding one of said pluralityof driven ring gears and reaction surface means positioned adjacent andin contact with said plurality of spring means.
 5. The two-wheel bicycleof claim 3, wherein said selective engagement means includes: a secondplurality of roller means for rolling contact with said plurality ofdriven ring gears, each one of said second plurality of roller meansbeing positioned adjacent to a corresponding one of said plurality ofdriven ring gears, guide means for maintaining each one of said secondplurality of roller means in alignment with said corresponding one ofsaid plurality of driven ring gears, cam means for selectively engagingone of said second plurality of roller means with said corresponding oneof said plurality of driven ring gears and for urging said correspondingone of said plurality of driven ring gears into contact with said firstdriven shaft and said second driven shaft, said cam means beingslidingly engaged with a track means, said track means being positionedadjacent said guide means, and a shift mechanism, said shift mechanismbeing mechanically associated with said cam means.
 6. The two-wheeldrive bicycle of claim 1, wherein said front wheel drive mechanismincludes: a universal joint, said universal joint having a first endconnected to said first driven shaft and a second end connected to saidfirst end of said first shaft means, a first intermediate shaft meansrotatably positioned in said steering head, said first intermediateshaft means having a first end and a second end, a first bevel gearconnected to said second end of said first shaft member and a secondbevel gear connected to said first end of said first intermediate shaftmeans, said first bevel gear and said second bevel gear being inoperable engagement with one another, a first spur gear connected tosaid second end of said first intermediate shaft means and a second spurgear connected to said first end of said second shaft member, said firstspur gear and said second spur gear being in operable engagement withone another, and a third bevel gear connected to said second end of saidsecond shaft means and a fourth bevel gear connected to said frontwheel, said third bevel gear and said fourth bevel gear being inoperable engagement with one another.
 7. The two-wheel drive bicycle ofclaim 1, wherein said rear wheel drive mechanism includes: a first spurgear connected to said second driven shaft and a second spur gearconnected to said first end of said third shaft means, said first spurgear and said second spur gear being in operable engagement with oneanother, and a first bevel gear connected to said second end of saidthird shaft means and a fourth bevel gear connected to said rear wheel,said first bevel gear and said second bevel gear being in operableengagement with one another.
 8. The two-wheel drive bicycle of claim 1,further including: a shock absorber positioned between said first end ofsaid seat stay and said seat tube and a hinge means positioned betweensaid first end of said hollow chain stay and said housing.
 9. The twowheel drive bicycle of claim 8, wherein said hinge means includes ahollow extension connected to said housing and wherein said rear wheeldrive mechanism includes: a fourth shaft means rotatably positionedinside of said hollow extension, said fourth shaft means having a firstend a second end, a first spur gear connected to said second drivenshaft and a second spur gear connected to said first end of said fourthshaft means, said first spur gear and said second spur gear being inoperable engagement with one another, a universal joint, said universaljoint having a first end connected to said second end of said fourthshaft means and a second end connected to said first end of said thirdshaft means, and a first bevel gear connected to said second end of saidthird shaft means and a fourth bevel gear connected to said rear wheel,said first bevel gear and said second bevel gear being in operableengagement with one another.
 10. The two-wheel drive bicycle of claim 1,wherein said front fork further includes a second hollow tubetelescopingly connected with said hollow tube and wherein said secondshaft means includes a first telescoping member and a second telescopingmember disposed axially and slidingly within said first telescopingmember, said first telescoping member and said second telescoping memberhaving spline means to prevent relative rotational movementtherebetween, said first telescoping member being operably connected tosaid front wheel and said second telescoping member being operablycoupled to said second end of said first shaft means.
 11. A two-wheeldrive bicycle, comprising: a main frame, said main frame including asteering head, a seat tube, a cross bar and a hollow downtube, saidcross bar having a first end and a second end, said first end of saidcross bar being connected to said steering tube and said second end ofsaid cross bar being connected to said seat tube, said hollow downtubehaving a first end and a second end, said first end of said hollowdowntube being connected to said steering head; front fork means forsteerably and rotatably connecting a front wheel to said main frame,said front fork means being pivotally connected to said steering head; afront wheel, said front wheel being rotatably connected to said frontfork means; rear frame means for rotatably connecting a rear wheel tosaid main frame, said rear frame means being connected to said mainframe; a rear wheel, said rear wheel being rotatably connected to saidrear frame proximate said second end of said chain stay; front wheeldrive means for rotatably driving said front wheel, said front wheeldrive means being operably coupled to said front wheel; rear wheel drivemeans for rotatably driving said rear wheel, said rear wheel drive meansbeing operably coupled to said rear wheel; and main drive means foroperating both said front wheel drive means and said rear wheel drivemeans, said main drive means being connected to said main frame andbeing operably coupled to both said front wheel drive means and saidrear wheel drive means.
 12. The two-wheel drive bicycle of claim 11,wherein said main drive means includes a housing, a driving spindle, atleast one driven ring gear, a first driven shaft and a second drivenshaft, said housing being connected to said main frame, said drivingspindle being rotatably connected to said housing and slidingly engagedwith said at least one driven ring gear, said first driven shaft beingrotatably connected to said housing and selectively engaged with said atleast one driven ring gear, and said second driven shaft being rotatablyconnected to said housing and selectively engaged with said at least onedriven ring gear.
 13. The two-wheel bicycle of claim 12, wherein saidfront fork means includes a first fork tube having a hollow portiontherein and wherein said front wheel drive means includes a first shaftmeans rotatably positioned inside of said hollow downtube and a secondshaft means rotatably positioned inside said hollow portion of saidfirst fork tube, said first shaft means having a first end operablycoupled to said first driven shaft and a second end, said second shaftmeans having a first end operably coupled to said second end of saidfirst shaft means and a second end operably coupled to said front wheel.14. The two-wheel drive bicycle of claim 13, wherein said rear framemeans includes a chain stay having a hollow portion therein and whereinsaid rear wheel drive means includes a third shaft means rotatablypositioned inside of said hollow portion of said chain stay, said thirdshaft means having a first end operably coupled to said second drivenshaft and a second end operably coupled to said rear wheel.
 15. Thetwo-wheel drive bicycle of claim 12, wherein said front fork furtherincludes a second fork tube having a hollow portion therein, said secondfork tube being telescopingly connected with said first fork tube andwherein said second shaft means includes a first telescoping member anda second telescoping member disposed axially and slidingly within saidfirst telescoping member, said first telescoping member and said secondtelescoping member having spline means to prevent relative rotationalmovement therebetween, said first telescoping member being operablyconnected to said front wheel and said second telescoping member beingoperably coupled to said second end of said first shaft means.
 16. Ashaft drive bicycle, comprising: a frame, said frame including asteering head and a hollow downtube, said hollow downtube having a firstend and a second end, said first end of said hollow downtube beingconnected to said steering head; a main drive mechanism, said main drivemechanism including a housing, a driving spindle, at least one drivenring gear and a first driven shaft, said housing being connected to saidframe, said driving spindle being rotatably connected to said housingand slidingly engaged with said at least one driven ring gear, saidfirst driven shaft being rotatably connected to said housing andselectively engaged with said at least one driven ring gear; a frontfork, said front fork including a hollow fork tube having a first endand a second end, said first end of said hollow fork tube beingpivotally connected to said steering head; a front wheel, said frontwheel being rotatably connected to said front fork proximate said secondend of said hollow fork tube; a rear wheel, said rear wheel beingrotatably connected to said frame; and a front wheel drive mechanism,said front wheel drive mechanism including a first shaft means rotatablypositioned inside of said hollow downtube and a second shaft meansrotatably positioned inside said hollow fork tube, said first shaftmeans having a first end operably coupled to said first driven shaft anda second end, said second shaft means having a first end operablycoupled to said second end of said first shaft means and a second endoperably coupled to said front wheel.
 17. The shaft drive bicycle ofclaim 16, wherein said main drive mechanism includes a plurality ofdriven ring gears, said plurality of driven ring gears comprising aseries of concentrically spaced ring gears, each ring gear of saidplurality of driven ring gears having an inner diametrical surface andan outer diametrical surface, each said outer diametrical surface beingconfigured to engage the inner diametrical surface of an adjacent ringgear.
 18. The shaft drive bicycle of claim 17, wherein said main drivemechanism further includes: biasing means for biasing each ring gear ofsaid plurality of driven ring gears away from said driven shaft andselective engagement means for selectively engaging one of saidplurality of ring gears with said driven shaft.
 19. A shaft drivebicycle, comprising: a frame, said frame including a steering head, aseat tube and a downtube; a main drive mechanism, said main drivemechanism including a housing, a driving spindle, at least one drivenring gear and a driven shaft, said housing being connected to saidframe, said driving spindle being rotatably connected to said housingand slidingly engaged with said at least one driven ring gear, saiddriven shaft being rotatably connected to said housing and selectivelyengaged with said at least one driven ring gear; a front fork pivotallyconnected to said steering head; a front wheel, said front wheel beingrotatably connected to said front fork; a rear frame, said rear frameincluding a seat stay and a hollow chain stay, said seat stay having afirst end and a second end, said first end of said seat stay beingconnected to said seat tube, said hollow chain stay having a first endand a second end, said first end of said hollow chain stay beingconnected to said housing and said second end of said hollow chain staybeing connected to said second end of said seat stay; a rear wheel, saidrear wheel being rotatably connected to said rear frame proximate saidsecond end of said chain stay; and a rear wheel drive mechanism, saidrear wheel drive mechanism including a shaft means rotatably positionedinside of said hollow chain stay, said shaft means having a first endoperably coupled to said driven shaft and a second end operably coupledto said rear wheel.
 20. The shaft drive bicycle of claim 19, whereinsaid main drive mechanism includes a plurality of driven ring gears,said plurality of driven ring gears comprising a series ofconcentrically spaced ring gears, each ring gear of said plurality ofdriven ring gears having an inner diametrical surface and an outerdiametrical surface, each said outer diametrical surface beingconfigured to engage the inner diametrical surface of an adjacent ringgear.
 21. The shaft drive bicycle of claim 20, wherein said main drivemechanism further includes: biasing means for biasing each ring gear ofsaid plurality of driven ring gears away from said driven shaft andselective engagement means for selectively engaging one of saidplurality of ring gears with said driven shaft.
 22. A transmission for abicycle having a frame and front and rear wheels, said transmissioncomprising: a housing, a driving spindle, at least one driven ring gearand a driven shaft, said housing being connected to said frame, saiddriving spindle being rotatably connected to said housing and slidinglyengaged with said at least one driven ring gear, said driven shaft beingrotatably connected to said housing and selectively engaged with said atleast one driven ring gear.
 23. The transmission of claim 22, whereinsaid transmission further includes a plurality of driven ring gears,said plurality of driven ring gears comprising a series ofconcentrically spaced ring gears, each ring gear of said plurality ofdriven ring gears having an inner diametrical surface and an outerdiametrical surface, each said outer diametrical surface beingconfigured to engage the inner diametrical surface of an adjacent ringgear.
 24. The transmission of claim 23, wherein said transmissionfurther includes: biasing means for biasing each ring gear of saidplurality of driven ring gears away from said driven shaft and selectiveengagement means for selectively engaging one of said plurality of ringgears with said driven shaft.
 25. The transmission of claim 24, whereinsaid biasing means includes: a first plurality of roller means forrolling contact with said plurality of driven ring gears, each one ofsaid first plurality of roller means being positioned adjacent to and incontact with a corresponding one of said plurality of driven ring gears,a plurality of spring means, each one of said plurality of spring meansbeing positioned adjacent to and in contact with a corresponding one ofsaid first plurality of roller means, guide means for maintaining eachone of said first plurality of roller means in alignment with saidcorresponding one of said plurality of driven ring gears and reactionsurface means positioned adjacent and in contact with said plurality ofspring means.
 26. The transmission of claim 25, wherein said selectiveengagement means includes: a second plurality of roller means forrolling contact with said plurality of driven ring gears, each one ofsaid second plurality of roller means being positioned adjacent to acorresponding one of said plurality of driven ring gears, guide meansfor maintaining each one of said second plurality of roller means inalignment with said corresponding one of said plurality of driven ringgears, cam means for selectively engaging one of said second pluralityof roller means with said corresponding one of said plurality of drivenring gears and for urging said corresponding one of said plurality ofdriven ring gears into contact with said driven shaft, said cam meansbeing slidingly engaged with a track means, said track means beingpositioned adjacent said guide means, and a shift mechanism, said shiftmechanism being mechanically associated with said cam means.
 27. Atransmission for a vehicle having a frame and at least one wheel,comprising: a housing, a driving spindle, a driven ring gear and adriven shaft, said driving spindle being rotatably connected to saidhousing and engaged with said driven ring gear, biasing means forbiasing said driven ring gear away from said driven shaft, andengagement means for engaging said driven ring gear with said drivenshaft.
 28. The transmission of claim 27, wherein said biasing meansincludes: roller means for rolling contact with said driven ring gear,spring means positioned adjacent to and in contact with said rollermeans, and guide means for maintaining said roller means in alignmentwith said driven ring gear.